scholarly journals Quantum Bose and Fermi gases with large negative scattering length in the two-bodyS-matrix approximation

2012 ◽  
Vol 86 (2) ◽  
Author(s):  
André LeClair ◽  
Edgar Marcelino ◽  
André Nicolai ◽  
Itzhak Roditi
Keyword(s):  
Scattering Length ◽  
Fermi Gases ◽  
Matrix Approximation ◽  
Negative Scattering Length

A systematic neutron reflectometry study on hydrogen absorption in thin Mg1-xAlx alloy films Special issue on Neutron Scattering in Canada.

2010 ◽  
Vol 88 (10) ◽  
pp. 723-728 ◽  
Author(s):  
H. Fritzsche ◽  
E. Poirier ◽  
J. Haagsma ◽  
C. Ophus ◽  
E. Luber ◽  
...  
Keyword(s):  
Hydrogen Absorption ◽  
Scattering Length ◽  
Catalyst Layer ◽  
Neutron Reflectometry ◽  
Hydrogen Distribution ◽  
Hydrogen Atoms ◽  
Alloy Films ◽  
Negative Scattering Length ◽  
Insight Into ◽  
Optimum Alloy

In this article, we show how neutron reflectometry (NR) can provide deep insight into the absorption and desorption properties of commercially promising hydrogen storage materials. NR benefits from the large negative scattering length of hydrogen atoms, which changes the reflectivity curve substantially, so that NR can determine not only the total amount of stored hydrogen but also the hydrogen distribution along the film normal, with nanometer resolution. To use NR, the samples must have smooth surfaces, and the film thickness should range between 10 and 200 nm. We performed a systematic study on thin Mg1–xAlx alloy films (x = 0.2, 0.3, 0.4, 0.67) capped with a Pd catalyst layer. Our NR experiments showed that Mg0.7Al0.3 is the optimum alloy composition with the highest amount of stored hydrogen and the lowest desorption temperature. All the thin films expand by about 20% because of hydrogen absorption, and the hydrogen is stored only in the MgAl layer with no hydrogen content in the Pd layer.

BOSE-EINSTEIN CONDENSATION OF ATOMS WITH ATTRACTIVE INTERACTION

1999 ◽  
Vol 13 (05n06) ◽  
pp. 625-631 ◽  
Author(s):  
N. AKHMEDIEV ◽  
M. P. DAS ◽  
A. V. VAGOV
Keyword(s):  
Statistical Physics ◽  
Scattering Length ◽  
Stationary Solutions ◽  
Attractive Potential ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Bose Einstein Condensation ◽  
Three Body ◽  
Negative Scattering Length ◽  
Bose Einstein

We suggest that crucial effect on Bose-Einstein condensation in systems with attractive potential is three-body interaction. We investigate stationary solutions of the Gross-Pitaevskii equation with negative scattering length and a higher-order stabilising term in presence of an external parabolic potential. Stability properties of the condensate are similar to those for thermodynamic systems in statistical physics which have first order phase transitions. We have shown that there are three possible type of stationary solutions corresponding to stable, metastable and unstable phases. Results are discussed in relation to recently observed 7 Li condensate.

scholarly journals Bose-Einstein Condensation of Confined Atomic Gases at Ultra Low Temperatures

2017 ◽  
Vol 9 (5) ◽  
pp. 96
Author(s):  
M. Serhan
Keyword(s):  
Low Temperatures ◽  
Chemical Potential ◽  
Scattering Length ◽  
Einstein Condensation ◽  
Pitaevskii Equation ◽  
Atomic Gases ◽  
Bose Einstein Condensation ◽  
Gaussian Type ◽  
Negative Scattering Length ◽  
Bose Einstein

In this work I solve the Gross-Pitaevskii equation describing an atomic gas confined in an isotropic harmonic trap by introducing a variational wavefunction of Gaussian type. The chemical potential of the system is calculated and the solutions are discussed in the weakly and strongly interacting regimes. For the attractive system with negative scattering length the maximum number of atoms that can be put in the condensate without collapse begins is calculated.

The energy of a unitary Fermi gas in the normal phase including the effect of induced interaction

2015 ◽  
Vol 29 (32) ◽  
pp. 1550207 ◽  
Author(s):  
Hao Gong ◽  
Xiao-Xia Ruan ◽  
Hou-Rong Pang ◽  
Hong-Shi Zong
Keyword(s):  
Experimental Data ◽  
Chemical Potential ◽  
Normal Phase ◽  
Fermi Gases ◽  
Matrix Approximation ◽  
Ultracold Fermi Gases ◽  
Self Consistent ◽  
Unitary Fermi Gas ◽  
T Matrix ◽  
Good Agreement

In this paper, taking into account the effect of the induced interaction, we calculate the energy of ultracold Fermi gases at unitarity in the framework of non-self-consistent T-matrix approximation (nTMA) above the critical temperature and compare the result with the experimental data and other theoretical calculation without induced interaction. Our calculated chemical potential is higher than the experimental data, but our calculated energy obtains a good agreement with Tokyo experiment for temperature range between [Formula: see text] and [Formula: see text].

scholarly journals Finite-range model potentials for resonant interactions

2016 ◽  
Vol 30 (08) ◽  
pp. 1650036 ◽  
Author(s):  
Bimalendu Deb
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Scattering Length ◽  
Atomic Gases ◽  
Finite Range ◽  
Threshold Behavior ◽  
Resonant Interactions ◽  
Scattering Phase ◽  
Tunable Interactions ◽  
Negative Scattering Length

We show that it is possible to model two-body resonant interactions at low energy with a class of finite-range potentials based on the methods of Jost and Kohn. These potentials are expressed in terms of the effective range [Formula: see text] and the [Formula: see text]-wave scattering length [Formula: see text]. We derive continuum solutions of these potentials. By writing [Formula: see text], where the sign [Formula: see text] refers to positive(negative) scattering length, [Formula: see text] is of the form of Pöschl–Teller potential and [Formula: see text] is expressed as a power series of the small parameter [Formula: see text] when [Formula: see text] is large, we derive Green’s function of [Formula: see text]. Using the Green’s function, solutions of [Formula: see text] for [Formula: see text] can be obtained numerically by treating [Formula: see text] as a perturbation. We describe the threshold behavior of scattering phase shift for [Formula: see text]. This study may be important for developing a better understanding of physics of strongly interacting ultracold atomic gases with tunable interactions.

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